ASME B30.26 maximum included angle for multiple slings in a shackle

• A. 90°
• B. 180°
• C. 120°
• D. 60°

Answer: (C)

When multiple slings share a single shackle, the way the load is distributed depends on the angle between the sling legs at the connection point. As this included angle increases, the force each leg (and the shackle itself) must carry grows, even if the vertical lifting capacity stays the same. This happens because the horizontal components of the sling forces add up, loading the hardware more heavily as the legs diverge.

To keep this loading within safe limits, standards specify a maximum included angle for any two sling legs in a shackle. The limit is 120 degrees. Keeping the angle at or below this value helps ensure the hardware isn’t overstressed and that each leg remains within its rated capacity. If you need a wider spread than that, you must reconfigure the rigging—add more shackles or use different hardware to maintain safe angles and load distribution. The angle is measured at the point where the sling legs enter the shackle, between any two legs.